The present invention relates to a knitting machine. More particularly, this invention concerns such a knitting machine having electromagnetically controlled needle position.
A knitting machine is known of the flatbed or circular type and having a housing on which is displaceable a support carrying a multiplicity of needles each carried on a respective needle holder. The support, in the case of a circular machine the cylinder, is displaceable in a support direction relative to the housing and the needles are displaceable in needle directions transverse to the support direction. Each of the needle holders is provided with a return foot that operates with a respective return cam to displace the needles and needle holders periodically into a bottom or cast-off position. It is furthermore known to provide each of the needle holders with an actuating foot that is displaceable relative to the needle holder in a direction transverse to the respective needle direction. A magnet is operable to displace this actuating foot into or out of a position engageable with a slide cam. When engaged with the slide cam the actuating foot causes the respective holder to be displaced up into the knit-tuck, or welt position. When the actuating foot is not engageable with the slide cam the respective needle and needle holder are not lifted and remain in the bottom position.
Such machines must invariably operate with relatively low speed as the electromagnetic actuation of the actuating feet cannot take place too rapidly. Furthermore, at high speed inherent vibrations and the like in the machine can frequently shake the actuating feet off the slide cam and cause the machine to mis-stitch.
Another difficulty with such machines is that the inevitable build up of dust and lint in them greatly slows down the cams in their grooves or raceways on the support. Thus it is necessary to provide extremely robust guide means and very powerful electromagnets to operate them in order to overcome the relatively high friction.
Various knitting machines can be seen in German Pat. Nos. 874,330 and 1,109,217, in German Published Specifications No. 1,585,208 July 30, 1970, No. 1,585,228 Aug. 6, 1970, No. 2,316,606 Oct. 11, 1973, and No. 2,327,585 Dec. 19, 1974, in German published applications No. 1,160,101 Dec. 27, 1963, No. 1,760,405 June 9, 1971, and No. 2,010,973 Jan. 27, 1972, and in U.S. Pat. No. 3,678,710.